Voltammetric determination of imidacloprid and thiamethoxam

Abstract

A simple voltammetric method using a glassy carbon working electrode was developed for the determination of two members from the neonicotinoid group of insecticides: imidacloprid and thiamethoxam. The experiments showed that the voltammetric response depends on the mode of electrode surface pretreatment and the polarization mode. The response appeared to be linear in the range from 0.028 to 0.50 mg/cm3 for both analyses. The limit of detection was 0.0077 mg/cm3 for imidacloprid and 0.0085 mg/cm3 for thiamethoxam, the limit of quantitation was 0.026 mg/cm3 and 0.028 mg/cm3, respectively. The developed method was applied for the determination of these insecticides in potato samples sprayed with Confidor 200-SL or Actara 25-WG as well as commercial formulations of imidacloprid and thiamethoxam. A recovery trial was performed to assess the accuracy of the results, the recovery values being between 95?102 % for both of neonicotinoids.

Monitoring of Photocatalytic Degradation of Selected Neonicotinoid Insecticides by Cathodic Voltammetry with a Bismuth Film Electrode

“…Since the reduction signal of acetamiprid is optimal at pH 3.0, a higher residual current affects the sensitivity of the method. In comparison with earlier data obtained with bare glassy carbon electrode for the determination of thiamethoxam and imidacloprid in potato samples [28] and acetamiprid in the Volley commercial formulation, it can be said that the BiFE is about 20 times more sensitive. Furthermore, the BiFE improves the reproducibility of the method about two times.…”

“…2). Such behavior can be explained by the significant role of protons in the complex reduction mechanisms [28,29,50]. Imidacloprid showed one irreversible reduction peak in a wide pH range between À 0.7 and À 0.9 V, the most intensive signal being obtained at pH 8.0.…”

“…To the best of our knowledge, no publications dealing with the electroanalytical monitoring of the photocatalytic degradation of neonicotinoids (imidacloprid and acetamiprid) have appeared so far. As these compounds have functional groups reducible in a fairly negative potential range, only the mercury [25,26,29] and glassy carbon electrodes [27,28] were applied for their determination. It is known that bismuth film on glassy carbon and carbon-based screen printed electrodes [30,31], likewise mercury film, improves the sensitivity of different types of stripping analysis methods, especially for a wide assortment of metal ions [32 -47].…”

Bismuth Film Electrode for the Cathodic Electrochemical Determination of Thiamethoxam

“…The methods that have been applied for its assay in agricultural and environmental samples involved high-performance liquid chromatography (HPLC) with diode-array [22,23] and mass-spectrometric [24,25] detection, as well as enzyme-linked immunosorbent assay [26]. The reduction mechanism of thiamethoxam at a dropping mercury electrode (DME) and its voltammetric determination either in model systems or thiamethoxam-treated samples, using glassy carbon (GCE) and static mercury drop electrodes (SMDE), were reported in our previous works [27,28].…”

A facile molecularly imprinted electrochemical sensor based on graphene: application to the selective determination of thiamethoxam in grain

“…15 Due to the irreversible electrochemical reduction properties of TMX, it can be eluted using electrochemical cyclic voltammetry. 28 As shown in Fig. 2a and b, compared with NIP-GN/GCE, there is a typical peak at À1.0 V to À1.2 V for MIP-GN/GCE during the rst scanning sweep, indicating that this peak is the characteristic peak of TMX.…”